Hydraulic tappet



. July 2, 1935. c. E. JOHNSON 2,006,641

HYDRAULIC TAPPET Filed Sept. 26, 1952 Patented July 2, 1935 UNITED STATES HYDRAULIC TAPPET Charles E. Johnson, North Muskegon,` lVIich. Application September 26, 1932, Serial No. 634,857

4 Claims.

This invention relates to hydraulic tappets and more particularly to such tappets used to operate poppet valves in internal combustion engines. The device embodying this invention is 5 of the same general nature as that disclosed in my copending patent application filed Jan. 11, 1932, Serial No. 585,859, in which hydraulic means are provided for automatically taking up all clearance between the valve tappet and the vention is to provide means forv eliminating air which inadvertently enters the hydraulic pressure medium such as oil used in the vpressure lubricating system of the automobile.

In the customary installation of a device of this nature in an internal combustion engine the conventional pressure lubricating system is utilized to furnish oil under pressure to the hydraulic means provided in the valve tappet and the small amounts of air which become mixed with the oil are detrimental to the perfeet operation of the valve tappet. The device depends for itsr operation upon the incompressible quality of oil and inasmuch as air lacks that quality and is compressible, when any considerable amount of it is contained in the oil within the valve tappet, it will permit relative movements of the parts which should not occur in perfect operation and for that reason it is desirable to eliminate the air which inadvertently enters vwith the oil into the hydraulic means of the valve tappet.

The invention provides various novel features of construction and arrangement as herein--` after more fully described and particularly pointed out in the claims, reference being had to the accompanying drawing, in which,

Fig. l is a vertical section of a portion of a conventional internal combustion engine showing a poppet valve, a cam and a valve tappet embodying this invention in operative position.

Fig. 2 is an enlarged elevation, partially in section, of a valve tappet embodying this invention shown in lowered position in its guide.

portion of the parts shown in Fig. 2 showing the valve tappet in raised position in its guide.,

valve stem and the principal object of this irl- Fig. 3 is a fragmentary section of the upper;

3 is arranged to close the opening 2 having a conventional seat at the edge of the opening. The valve stem 4 passes through a valve stem guide 5 and is provided with a valve spring E which springseats at its upper end against a xed part ofthe engine and at itslower end on a spring seat 'I fastened to the valve stemlI. A cam 8 on a cam shaft 9 is located below the valve stem 4 and a valve tappet is interposed between the cam 8 and the lower end of thervalve 10 stem 4.

The tappet comprises a body III which is mounted for vertical sliding movement in a tappet guide II.` The upper end of the tappet body III is provided with an axial opening in 15 which is located a slidable plunger I2. A check valve cage 'I3 is located in the opening below the plunger I2, said opening being of slightly reduced diameter at the location of the cage and the cage being of exterior diameter to pro- 20 vide a press t into said reduced portion of the opening. The cage has 'an axial opening I4 which is reduced to provide a seat I5 for the ball check valve I6 and lateral openings Il are provided below the ball I6 which communicate 25 withv lateral openings I8 vwhich extend through the body I0 of the tappet and communicate with an Vannular groove I9 therein.

`A small rod or pin 20 extends across the opening I4 of the cage a short distance above 30 the ball I6 to limit the movement of the ball in Aa direction away from its seat. A passage 2| is in communication with the oil pressure lubricating system of the engine and leads to the, interior of the tappet guide II at a point 35 where it will communicate with the annular groove I9 in the tappet body so that oil under pressure will be conducted into the interior of thetappet body through the passages I8 and I'I- and past the ball check valve I6.V

As previously stated1 the valve tappet is interposed between the cam 8 and the lower end ofthe valve stem IV and it is of proper length that, when the slidable plunger I2 is in retracted or lower position and when the cam is in posi- 45 tion to lower the tappet, there will be a slight space or clearance between the upper end of the plunger I2 and the lower end of the valve stem 4. The plunger is moved upwardly relative to the tappet body I0 or extended by force 50I of the oil pressure within the tappet body which acts upon the lower end of the plunger. Movement ,of the plunger is limited by a re tainer which is in the nature-ofl a ring 22 surrounding the upperendof the YtappetV body 55l into an annular groove 24 in the plunger I2.

. outward direction.

'Ihe width or vertical dimension of the groove 24 is suiiicient to permit movement of the plunger I2 within the desired operating range but will prevent movement of the plunger beyondthat range especially in an upward or The plunger in its downward or inward movement may be stopped by the en d 23 of the retainer or the lowerk end of the plunger may engage against the upper end of the valve cage I3 as shown in Fig. 3.

A central opening 25 is. provided in theA plunger. extending upward from its lower endf into which the oil will rise and also any air which may be contained in the oil will rise into this opening 25 by reason of the diilerences in specific gravity and at the -upper end of the.

opening 25 a small outlet opening 28. is.pro.v vided which extends through the body of the plunger and communicates `V`with, an annular. groove 21 inthe outer surfaceof the plunger..

A passage 28 is vprovided through the wall of the tappet body VI IJ in a position where it willcommunicate withthe groove 21 whenthe` plunger is in lower position but said groove willV be out of communication with the passage 28 when the plunger is raised. The outlet opening '26, the groove 21.#and passage 28 are for the purpose of permitting the escape .of air from vthe interior of the device and it may be here stated that the air will escape from the passage 28 between the tappet I0 and .the tappet guide I I since there must be some 4loosenessgor clearance in the t of the tappet in the 4tappet guide for proper operation, such.. clearance being suf.

icient to permit the escapeY of small quantities of air which are Vto be eliminated.Y However, the clearance is not suflicient to permit. any material quantity of'oil to. escape from the ing let passage 2| and thus the oil pressure will be transmitted to a point underneath theplunger I 2 to cause its upward movement.

Before the engine' commences to run, and especially if it has been standing idle for'sorne time, the pressure will have vanished from the lubricating system 'whichisin' communication with the interior of the tappet I`which permits the plunger VI2 to recede or lower causing a. gap between the upper end of the Vplunger' and the lowervend of the valve'steml Immediately upon beginning operation of the engine a pressure is attained in the pressure lubricating system oi' the engine and alsoV within the `valve tappet which causes the lplunger-to rise into close engagement with the lowerend of the valve stem. The pressure-of the oil in Vthe system is not sufficient to raisezthe'valv'e spring- 8 but will act to lift the weight of the plunger I2 until it isstopped by engagement with the valve stem 4. 'I'he oil toy produce this `lifting'v action has entered fromthe passage 2| into the annular groove I9- and thence passes through' the passages I8 'and I1 and past th ballcheck valve I6Y into. the interior of the tappet body I8 and vthe ball check valve I8 prevents return move- `ment of the oil and `traps, the oil which has en-` tered to hold'the plunger I2 to the positionto which it has been extended because of the incompressibility of the oil. Action of the cam 8 Vto raise the tappet body thenf lifts the valve 3 compressing the `valve spring 6, this action being exerted through theji plunger I2 fand the oilv trapped under it withinrthetappet body.

The upward movement of the plunger vto engage with the valve stem has caused the groove 21 to move out of communication with the passage 28 and therefore prevents the escape 'of oil through the outlet opening .26. operates the cam repeatedly lifts the tappet I0 and then lowers it causing a similar action of the valve 3. During the period when the cam holds the tappet in raised position a considerable force is applied downwardly on the plunger I2 but thisforce is resisted bythe oil trapped below the plunger by the ball check valve I6. During the intervals between the raised position of the tappet and when the valve 3 rests upon its seat, there-is no downward thrust by the valve against the plunger I2 and the pressure of the lubricating system is suilicient to renew the supply of oil under the plunger I2 toV take the place of any leakage which may have occurred by supplying additional oil underV pressure past the ball check Vvalve I6 and thus the plunger. I2

is maintained in constantengagement with theA valve stem 4 during the operation of the engine.

'I'he foregoing description of theoperation is asitwould occurY providing that there were no airl miredv with the oil in the space below the plunger I2 and above the ball I6. Entrance of.r

As the `engine,

airmixed with the oil into that space Yin `any'` appreciable quantity will cause the oil, so mixedV with air, to have the quality. of being compressed."

When this occurs the considerable,force-.exerted downwardly upon the plunger I2 when the cam' 8 raises the tappet will cause the plunger I2 to'.v

lower within the tappet body because of Ythe compressible quality of the oilr mixed with air, to a position shown in Fig; 3 which will cause communication between the groove 21 and the passage 28 permitting the escapeof air or -combined oil and air from the interior of the tappet.'

It is assumed that the air will separate Vvfrom the oil to a large extent, by reason of the differences in their specic gravity, and rise to the top of the opening 25 so that-the air will be expelled through the openingY 26 and the oil within the tappet body cleared 'from its air content within a reasonably short time. interval of lowered tappet'position the part of the contents of the interior of the tappetV which has been expelled as Vdescribed through the outlet 26 will be replenished byroil injected past the 'ball valve I8 and -when substantially all of the .air

has been separated fronrthe oil,` which oil will During Veach.

passage 28 and the oil -will be positively trapped Y within the tappet body excepting Vfor such small leakage as mayV occur, either around the plunger I2 or past the ball valve I6. lAny'entrance of air into the tappet chamberin suiiicientquan-I tity to permit yielding of the p1unger'I2 in Va. downward direction will automatically Vcause communication between the groove 21 and the passagev 28 whereby such air will be expelled through the outlet opening 26 and Vtheexpelled air will be .replaced by additional oil "suppliedratV the rest position of the tappet. The invention has been described as embodied in a tappet for operating the poppet valve of an internal combustion engine but it is conceived that the same invention will be applicable to other devices. In any mechanism in which one part is to be moved by action of another part and wherein clearance between the parts is to be eliminated and especially where there may be an alteration in the dimensions of the parts due to change of temperature, wear, etc., which would make a permanent adjustment impossible, a device made in accordance with this invention is applicable.

It is also conceived that other sources of pressure than the pressure lubricating system of an engine may be utilized to Vsupply fluid under pressure to the device and its operation. Even when the tappet is used in an internal combustion engine having a pressure lubricating system it may be desirable to supply uid pressure for the tappet mechanism by some other suitable means.

It is to be understood, of course, that the tappet will probably be used in multiple in an internal combustion engine, one tappet being used for each valve and that when so used a common source of fluid under pressure supplies all of the tappets.

The invention is dened in the appended claims and is to be considered comprehensive of all forms of structure coming within their scope.

I claim:

1. A device of the class described comprising, a body having an interior opening, a plunger slidably mounted in said body and extending into said interior opening, means for supplying oil into said interior opening to extend said plunger, a second means for carrying away oil from said interior opening, and a third means controlled by movement of said plunger for closing the second means when the plunger is extended and for opening the same when the plunger is retracted.

2. A tappet comprising, a tappet body having a normally vertical axis, an axial opening extending into said tappet body from the upper end thereOf, a plunger extending into said axial opening and vertically movable therein, means for feeding oil into said axial opening below said plunger, means for trapping oil fed into said axial opening, a recess in the lower end of said plunger, an outlet passage in the plunger communicating with the upper portion of said recess, and a passage through the tappet body in a position to communicate with said outlet passage in the plunger when the plunger is in relatively retracted lower position and to be out of communication with said outlet passage when the plunger is in extended raised position.

3. A tappet comprising, a tappet body having an axial opening extending through the upper end of said tappet body, a plunger slidably mounted in said axial opening, means for introducing oil into said axial opening below said plunger, check valve means for trapping oil introduced into said axial opening, an opening in said plunger extending upwardly from the lower end thereof and closed at its upper end, an annular groove in the outer surface of said plunger, a passage communicating between said annular groove and the upper portion of said opening in the plunger and a passage through the wall of said tappet body located in a position t0 communicate with said annular groove when the plunger is in relatively retracted lower position, said annular groove being out of communication with said passage in the tappet body when the plunger is in relatively extended raised position.

4. A valve tappet of the class described comprising, a tappet body having an interior opening, a plunger slidably mounted in said tappet body and extending into said interior opening, pressure means for introducing oil into said interior opening to extend said plunger and outlet means leading from said interior opening, said plunger rendering the outlet means inoperative at a certain predetermined range of positions.

CHARLES E. JOHNSON. 

